After Antiochus
XI was killed (92 BCE), Cleopatra IV supported the attempt of his
younger brother, Philip -- the third son of Antiochus
VIII -- to regain control of Syria from his cousin Antiochus
X. He succeeded in occupying much of western Syria but faced additional
competition from his own younger brother Demetrius
III, who was supported by Cleopatra's son & rival Ptolemy
VII.
After the death of Antiochus X, he & Demetrius divided Syria between
them. When Demetrius sought to take sole control of the Seleucid empire,
however, Philip defeated & exiled him with the aid of the Parthians (87BCE).
Philip then claimed Antioch, but before he could consolidate his
power he faced a new rival in the person of his youngest brother Antiochus
XII, who seized control of Demetrius' former capitol, Damascus. Though Philip
briefly occupied Damascus while Antiochus was off fighting the Arabs, he
was forced to abandon it when his younger brother returned. That
humiliation encouraged the citizens of Antioch to drive him into exile
& recognize Tigranes of Armenia as their ruler. Though Philip outlasted his sibling rivals, he could not effectively control the
Seleucid empire but was at best a client & pawn of other powers.

Silver tetradrachma
of diademed Philip I with figure of enthroned Zeus on reverse
side, flanked by the inscription (reading from right to left) Baslieou
Philippou Epiphanou Philadelphou ["of King Philip
Philadelphos (God) Manifest"]. Ironically when Rome
conquered Syria they continued to mint copies of this coin
proclaiming the divinity of one of the last & weakest of Seleucid rulers.